Disclosed is a client device that includes: a user interface to receive a username and a first password associated with a server site visited by a user; a random number generator to generate a random number; and a processor to generate a second password by implementing a function based upon the first password and the random number and to command storage of the random number, the username, and the associated server site. If the user attempts to log onto the server site by inputting their username and the second password, the processor extracts the random number associated with the username and the server site and implements the function based upon the second password and the random number to generate the first password which replaces the second password entered by the user and is submitted to the server site.